In Design Mode, you can add elements (or controls) to your page. Each element has several properties. Most often, you configure your elements by working with Property Explorer. However, you can also manipulate properties in script using the following functions:

GETPGets the referenced property value
SETPSets the referenced property to the specified value.
IPageElementParameter.Value PropertyGets/sets the property value by working directly with the property object via the _members--IPageElementParameter interface members.